Diagnostic trouble codes or On-board diagnostics refer to a vehicle’s self-diagnostic and reporting capability. On-board diagnostics (OBD) is an automotive term referring to a vehicle’s self-diagnostic and reporting capability.
OBD systems give the vehicle owner or repair technician access to the status of the various vehicle sub-systems. The amount of diagnostic information available via OBD has varied widely since its introduction in the early 1980s versions of on-board vehicle computers. Earlier versions of OBD would illuminate a malfunction indicator light or “idiot light” if a problem was detected but would not provide any information as to the nature of the problem.
OBD systems give the vehicle owner or repair technician access to the status of the various vehicle sub-systems. The amount of diagnostic information available via OBD has varied widely since its introduction in the early 1980s versions of on-board vehicle computers. Earlier versions of OBD would illuminate a malfunction indicator light or “idiot light” if a problem was detected but would not provide any information as to the nature of the problem. Modern OBD implementations use a standardized digital communications port to provide real-time data and a standardized series of diagnostic trouble codes, or DTCs, allowing a person to rapidly identify and remedy malfunctions within the vehicle.
Modern OBD implementations use a standardized digital communications port to provide real-time data and a standardized series of diagnostic trouble codes, or DTCs, allowing a person to rapidly identify and remedy malfunctions within the vehicle.
Standard interfaces of On-board diagnostics
In the history of Standard interfaces of Onboard diagnostics, we have ALDL, OBD-I, OBD-1.5, and OBD-II.
OBD-II is an improvement over OBD-I in both capability and standardization. The OBD-II standard specifies the type of diagnostic connector and its pinout, the electrical signaling protocols available, and the messaging format. It also provides a candidate list of vehicle parameters to monitor and how to encode the data for each.
The OBD-II specification provides for a standardized hardware interface — the female 16-pin (2×8) J1962 connector, where type A is used for 12 Volt vehicles and type B for 24 Volt vehicles, presents on OBD-II diagnostic connector.
In Japan, we have JOBD, a version of OBD-II for vehicles sold there. The European on-board diagnostics (EOBD) regulations are the European equivalent of OBD-II.